Boot Process For The Ertec 200P; Table 2: Boot, Ertec 200P Boot Modes - Siemens ERTEC 200P-2 Manual

2.3.1.5 Boot Process for the ERTEC 200P

A primary boot loader is integrated into ERTEC 200P (8 KByte boot ROM at the APB).
The ERTEC 200P can be booted with a number of boot media and the boot modes re-
quired for the various different configurations are therefore supported.
Booting is possible with one of four sources:
Boot
mode
...from the external NOR flash conneted to
1 ... 2
... from firmware copied to the TCM over the
5, 6 SPI master interface of the ERTEC 200P
... from an external host CPU that loads the
7
firmware to the TCM over the XHIF
Booting can be triggered by:
HW reset (PowerOn reset, XRESET)
Watchdog reset (WDT expires)
Software reset
The complete list of reset triggers can be found in 2.3.10.9.4 and in the CRU (2.3.9.4).
From the boot ROM, ARM926 processes the primary boot loader, which loads a second-
ary boot loader from the corresponding boot medium to the D-TCM (Block3:
0x0803_0000) so that, after the switch to I-TCM (Block0: 0x0000_0000), the secondary
boot loader is saved after the interrupt jump table (see 2.3.1.5.1). If an external host is
responsible for booting, it transfers the secondary boot loader to the D-TCM (Block3:
0x0803_0000).
Once the secondary boot loader has been loaded, this 64 KByte segment is switched to
the I-TCM and is shown at address 0x0000_0000. The secondary boot loader loaded is
not lost when the system switches to the I-TCM. Following a PowerOn reset, the TCM926
configuration is 256 KByte D-TCM. As the assignment of the SRAM blocks in the I-TCM
and D-TCM is completely reversed, the boot loader must copy the code image in
64 KByte blocks from the bottom D-TCM Block3 (0x0803_0000)
(0x0800_0000), i.e. in ascending order. The address order is not reversed in the TCM
block. After download to the D-TCM, the final TCM926 configuration is set in
TCM926_MAP (see 2.3.10.9.14). The boot loader must then display the TCM memories
in the address range of the coprocessor interface (CP15 c9).
The primary boot loader then transfers to the secondary boot loader loaded in which the
user then continues booting on an application-specific basis. One task of the secondary
boot loader is to copy a code image to the I-TCM. There are two options available here:
The secondary boot loader sets the final TCM926 configuration required in
TCM926_MAP (see 2.3.10.9.14). The code image can then be transferred by the
boot medium to the I-TCM after the secondary boot loader.
Copyright © Siemens AG 2016. All rights reserved
Technical data subject to change
Booting...
the EMC

Table 2: Boot, ERTEC 200P boot modes

32
Use case
Use case 2
(Standalone Application)
Future use case, for ex-
ample for low-cost appli-
cations
Use case 1
(External Host)
D-TCM Block 0
ERTEC 200P-2 Manual
Version 1.0